Synthesize, procure test, and distribute radiolabeled materials. Such- radiolabeled materials are use by intramural and extramural investigators for preclinical and clinical pharmacological studies. Assignments for preparation or procurement of radiolabeled materials are made by the Project Officer and include a wide variety of chemicals and radioactive atom with the major emphasis being on the preparation of the desired labeled materials via synthetic procedures using 14C and tritium. Major emphasis will be on the preparation of the desired radiolabeled compounds via synthetic procedures and will involve a wide variety of compounds. Compounds required may include one or more radioactive elements. Methods of synthesis will be available for "cold runs" in many, but not all, instances. Development of new and/or existing synthetic procedures shall be required. Operate a preparation laboratory for the synthesis of radiolabeled materials. Approximately 5 to 10 radiolabeled preparations per year should be anticipated. Provide storage and distribution of radiolabeled materials for approximately 50 compounds. Weight, package and label all shipments, approximately 10 shipments per month should be anticipated.